Once May gets underway flue-cured tobacco producers in eastern North Carolina know they have to keep their eyes peeled for insect problems. In fact, assistant extension agent Tim Britton of the Southeast District (Johnston County) reports that by May 17, Johnston County growers had already seen flea beetles, cutworms, grasshoppers, budworms and hornworms on tobacco.
Britton notes the following remedial treatment recommendations by NCSU extension for tobacco in eastern North Carolina:
• Tobacco/tomato hornworms: Treatment is justified when one or more hornworms larger than 1 inch and without parasite cocoons (Cotesia) are found per 10 plants checked. Since worms with parasite cocoons eat much less, they should be counted as 1/5 of a worm (that is, five worms with cocoons equal one healthy worm).
• Flea beetles: Treat when small plants average four or more beetles per plant. Treat large plants when there are 60 or more beetles per plant or when the lower leaves begin to look ragged or lacy at the base (near the stalk).
• Aphids (plant lice): Treat when 10% or more of plants have as many as 50 aphids on any upper leaf before topping. Do not wait until hundreds of aphids are present to count a plant infested. This threshold should be used carefully. Before topping, populations can increase rapidly beyond 10 percent infestation. Do not delay initiating treatment.
• Japanese beetles, loopers, and grasshoppers: No exact thresholds have been established but, as a rule, treat when anticipated damage is equal to or greater than that caused by a 10% budworm infestation.
• Cutworms, vegetable weevils, mole crickets, and slugs: Treat when 5% or more of small plants (within 3 weeks of transplanting) are killed or injured.
For more information about insect challenges in flue-cured tobacco see Chapter 9 of the Flue-Cured Tobacco Guide 2010, available from your local extension agent and also online.
Download the guide in .pdf form at ipm.ncsu.edu/Production_Guides/Flue-Cured/flue_cured.pdf.